If you are looking for a hasselblad set up i would probably go with the 500cm, WLF (waist level finder), or a prism finder, a12 back, and a 80cf lens.

For the finder. I prefer using the WLF as that is they way that i like to work. If you like looking into a view finder, i would go with the NC2. It is a very basic 45 degree finder.

The 80 lens is the normal lens on a 6x6 camera. So if you like shooting a 50 on 35mm format, the 80 is for you. If you like shooting longer or wider then normal you still have a lot of choices in lens. Like the 50 for a wide and a 150 for a longer.

A second on that. The 500cm is a good intro to medium format shooting (the elm or elx is better suited to commercial work: noisy, heavy and best wedded to a tripod). If you take a liking to the Blad system you can expand your system, as suggested, to the holy triumvirate of the 50/80/150 or, if money is less a concern (or interest warrants) to the 50/80/120M/180). Extra backs, of course, are always a good investment - and relatively cheap.